1. Field of the Invention
The invention relates to a method and apparatus for laser welding thermoplastic resin members. In particular, the invention relates to a method and apparatus for joining a member formed of a transmissive thermoplastic resin that transmits a laser beam with a member formed of an absorptive thermoplastic resin that absorbs a laser beam by melting them.
2. Background Art
In response to the demand in recent years for reducing the weight and cost of components in various fields, such as automobile components, such components are often made of resin materials and formed as resin molded items. When a resin molded item having a complex shape is to be formed, a plurality of component parts of the resin molded item are molded in advance and then jointed together by welding for productivity enhancing purposes.
Conventional laser welding apparatuses for welding this kind of resin molded items weld members to be processed by focusing a laser beam produced from a laser oscillator with the use of an optical system, and then irradiating the members therewith. A slidable portion on the members to be processed is provided at the tip of a processing nozzle disposed between a focus lens of the optical system and the members to be processed. A pressure-applying device is also provided for applying pressure on the members to be processed against the slidable portion at the processing nozzle tip (see Patent Document 1, for example).
In another example of a laser welding apparatus, an area of contact of at least two works is irradiated with a laser beam through one of the works so as to melt the contact surfaces and weld the works. The apparatus comprises a laser beam generating means for generating a laser beam, and a spherical lens disposed directly underneath where the laser beam exits the laser beam generating means for focusing the laser beam at the contact area. The spherical lens is adapted to roll on the surface of the work that transmits the laser beam. The apparatus further includes a pushing means for pushing the spherical lens against the work (see Patent Document 2, for example).
Patent Document 1: JP Patent Publication (Kokai) No. 2003-117674 A
Patent Document 2: JP Patent Publication (Kokai) No. 2005-81396 A